Palissage experiment

Summary

Justine Vanden Heuvel, Associate Professor of Viticulture, called for vineyards to participate in a project on palissage. She asked growers to experiment with this method and share their observations with her and her graduate student Justin France.
This report describes the experimental setup and results with one of the two types of palissage; wrapping the shoots around the top wire.

At ‘De Achthoeven’ vineyard two grape varieties were choosen, Marechal Foch and Solaris, based on their vigorous growth and tendency to form lateral shoots.

Both grape varieties showed a reduction in growth of lateral shoots in the vertical part of the canopy when palissage was applied. The effect is larger with the Marechal Foch.
Although no diseases were found (up to the time of writing this report), the dense canopy with palissage is a concern. The additional weight causes stretching of the top wire. When palissage is choosen, the supporting trellis system needs to be strenghtened.
No reduction in the time required for attending the vines was observed.

For the grape variety for which separate measurements were performed at harvest, no significant differences in quantities, sugar levels and acidity were observed between the two rows.

Experiment

Experimental setup

Grape varieties

Two grape varieties, Marechal Foch and Solaris, were chosen for the experiment because of their vigorous growth and strong tendency to grow axillary shoots and form a dense foliage. Both grapes grow on SO4 rootstock.

Palissage type

The four rows, with each 10 grapes, are planted in North-South direction, with prevailing winds from the South-west. The two outer rows were chosen for palissage, the two inner rows for the ‘control’ (traditionally pruned) vines.

The type of palissage is with the shoot tips wrapped horizontally along the top wire at 2m.

Soil type

Soil type is a so-called “Enkeerdgrond” (approx. 40-50 cm humus-rich brown-colored layer of soil on sharp sand. These soils are the result of fertilization of poor earth with manure and sod during centuries of human occupation.). This soil-type is not very fertile, a bit acidic (pH approx 6) and minerals are washed out easily. The drainage is very good.

Growing season

The growing season started half of April, a bit ahead of the long-time average, after a long, but mild winter. The months of May and June were a bit cooler than average, but with a lot of sun and little rain. July was hotter than average and again dry.
A major part of the 2015 growing season in The Netherlands was amongst the 5% driest years since measurements began in 1705. But this changed at the end of July. The first serious rain (30mm in one day) came at the end of July and in the second half of August. From then on, we had sunny periods and perdiods with intense showers. During the rainy periods the temperatures were more or less normal, resulting in increased risk of diseases in the vineyard.
From September onward, this type of weather with alternating sunny and dry periods continued. The temperatures were slightly lower than the long-time average.
The amount of rain and sun during the growing season are shown in the next two figures.

The rainfall deficit, averaged over the entire Netherlands, is shown in the following figure (figure 1) by the black line. The blue line shows the median.

figure 1. The rainfall deficit for 2015, compared with the median and extreme years

The next figure (figure 2) shows the Huglin-index, a measure for the temperature during the growing season. The Huglin-index is similar, but not identical, to the Growing Degree Days measure. The plot shows the long time average (dark red line), the curve for this year (light red) and a shifted curve of the long time average that goes through the current value (dark red dotted line) and which shows the difference in days between the current value of the Huglin-index and the long time average.
The plot also shows the Huglin-index at harvest for some hybrid and common grape varieties.

figure 2. Huglin-index during the growing season 2015 (source: measurements by BvH, climate-data by the KNMI)

The “Huglin” plot also shows the different growth phases for the Rondo grape, which is an “early” grape variety like the Solaris and Marechal Foch varieties (the data are based on private measurements between 2009-2014). These varieties all have approximately equal bud-break. The Solaris ripens about one to two weeks earlier, the Marechal Foch ripens about one or two weeks later than the Rondo.

BBCH-scale	Dutch	English	M.Foch	Solaris
05	wol-stadium	wool stage	10-4-2015	10-4-2015
09	knoppen breken	bud break	22-4-2015	23-4-2015
11	1e blad	first leave	25-4-2015	27-4-2015
13	3e blad	third leave	1-5-2015	5-5-2015
15	5e blad	fifth leave	11-5-2015	13-5-2015
61	10% bloei	10% flowering	6-6-2015	10-6-2015
68	80% bloei	80% flowering	14-6-2015	25-6-2015
73	korrelgrootte	groat-sized berries	24-6-2015	30-6-2015
83	verkleuring	‘veraison’	10-8-2015	30-7-2015
89	oogst	harvest	11-10-2015	20-9-2015

Vineyard activities

Pruning

The first shoots reached the top wire around June 5th. The first hedging took place on July 10th. At that time, the shoots were 100-150cm ‘above’ the top wire.
Both the ‘inner’ rows were hedged manually with a hedge trimmer. Both the ‘outer’ rows were wrapped manually.

The following table shows the time spent on hedging and wrapping:

variety	method	time/vine (minutes)	ease
M.Foch	hedging	1.5 a 2.0	2
M.Foch	wrapping	2	5
Solaris	hedging	1	2
Solaris	wrapping	2.5	5

with the ease of applying the method described on a scale 1 to 10, where 1 is technically easy and quick, where 5 took some technical learning and time, and where 10 is difficult and time consuming.

Notes:

1. the time spent on hedging included disposal of the removed shoots.
   
2. with hedging, my only concern is to minimise damage to the top leaves and to keep the distance to the top wire about equal.
3. wrapping required more ‘thought’ and attention, although its not the first time I used this method (which was in 2014, after a suggestion in a tweet by Justine Vanden Heuvel). The attention is needed to prevent the shoots from breaking and to wrap all the shoots in the same direction (to prevent a build-up of shoots in certain parts of the caopy).
   The direction of wrapping was towards the North, based on the idea that pointing the top away from the light would slow down growth.
   
4. with wrapping, the top of the canopy becomes quite dense. The reason is because 100-150 cm long shoots had to be wrapped around the top wire.
   
5. the number and size of laterals was already high. All laterals in the fruit zone (lowest 45cm) were either removed or cut back to one leave.

The following photo’s show the rows before and after the pruning activities.

variety	before	after
M.Foch
Solaris

The following photo shows a close-up of the wrapped Marechal Foch.

The following photo’s show the amount removed shoots for both hedging and palissage (unfortunately, these have not been weighted).

variety	hedging	palissage
M.Foch

A second round of hedging took place on August 11th. Before hedging, the following observations were made:

Marechal Foch:

type	description
hedging	longer laterals, with length up to 70-100cm, present. Stil, the canopy in general is more open. No diseases present.
wrapping	shorter laterals, with length up to 25-30cm, present in vertical part of the canopy. Many and long laterals present in wrapped shoots. Very dense canopy around the top wire. No diseases present.

Solaris:

type	description
hedging	less new top-laterals than with the M.Foch, a bit more laterals than with wrapping, but less obvious differences than with the M.Foch. Relatively open canopy. No diseases present.
wrapping	Very dense canopy around the top wire. The canopy is slightly more open than with the hedged vines, but the difference is nullified by top shoots that that have sagged. The result is a very dense canopy, also in the vertical part. No diseases present.

Notes:

1. Where M. Foch tends to form laterals, the Solaris tends to continue growing the primary shoot, resulting in very long shoots that fall downward. This results in a combination of ‘wrapping’ and ‘circling’.
   
2. to reduce the risk of fungal diseases, a hedging of all the rows in this experiment was needed.
   
3. with wrapping, the top wire has to carry a really heavy load. When pallisage is choosen, it’s recommended to either double the top wire, or select a wire with a diameter of minimally 5mm. My top wire is, like all my wires, 3 mm and got stretched.

All vertical top shoots, laterals in both ‘wrapped’ and ‘hedged’ rows, were shortened manually with the hedge trimmer. Laterals in the vertical part of the canopy were either removed or shortened to one or two leaves.
Wrapped shoots that had become to long and circled downward were shortened, both to open up the canopy and to relieve the top wire from a too heavy load.
The time required to prune the hedged and palissage rows was about equal. In both cases both the top-laterals and the laterals in the vertical part of the canopy needed trimming. Where with the hedged rows there were slightly more laterals in the vertical part, the palissage rows needed more time to clear the laterals from the wrapped shoots and to shorten these.

The following photo’s show the rows of Marechal Foch before and after the pruning activities. The photographs are taken close to the rows to give an impression of the width of the row. Over the last month the rows have become wider due to growth of the older leaves and the growth of laterals. It can be seen that both the top laterals and side laterals have been removed. It can also be seen that the top line on the right has dropped a bit in the middle.

type	before	after
hedged
wrapped

The following photo’s show examples of laterals for the hedged and wrapped vines.

variety	hedged	wrapped
M.Foch
Solaris

The following photo show examples of the top of the canopy for the hedged and wrapped vines of the Solaris. Both photo’s have been taken from the same height and at the same angle, but in opposite directions with respect to the position of the sun, resulting in unnatural colors. The top of the wrapped vines is denser.

variety	hedged top	wrapped top
Solaris

In most years, both Marechal Foch and Solaris need two or three rounds of hedging and trimming of laterals. This year, I let the shoots grow a bit more before hedging in the hope to find more distinct differences between hedging and palissage.
It’s expected that from now one the growth of the vines has more or less ended and the energy is put into ripening the berries.

Spray schedule

The following spray schedule was applied to the entire vineyard (100 grapes):

date	what	amount	reason
10-4	sulphur	5ml/L	preventive against Oidium
10-4	Rapsöl	100ml/L	preventive against mites and to delay bud-break
8-6	Magnesium-phosphite	2ml/L	applied on leaves, preventive against Peronospora and Mg difficit
9-6	sulphur	5ml/L	applied on leaves, preventive against Oidium
21-7	Scala	2ml/L	preventive against botrytis in bunches (applied at BBCH 77 - bunch closure)
21-7	Magnesium-phosphite	2ml/L	applied on leaves, preventive against Peronospora (high temp. and humidity)
14-8	Magnesium-phosphite	2ml/L	applied on leaves, signs of Mg difficit
14-8	Copper-phosphite	1ml/L	applied on leaves, preventive against Peronospora

No diseases were found on the grape varieties Solaris and Marechal Foch. The same schedule was applied on the other grapes in the same vineyard. The Golubok and Johanniter showed a very mild infection with black rot. The Golubok also showed some Peronospera in the young leaves.

Final results

The results are described separately with respect to the findings in the vineyard and in the winery, because not only the work in the vineyard counts, but also the quality of the grapes.

Canopy

The main observations are as follows;

1. Both grape varieties showed a reduction in growth of lateral shoots in the vertical part of the canopy when palissage was applied. The effect is larger with the Marechal Foch.
   
2. Although no diseases were found (up to the time of writing this report), the dense canopy with palissage is a concern. The additional weight causes stretching of the top wire. When palissage is choosen, the supporting trellis system needs to be strenghtened.
   
3. No reduction in the time required for attending the vines was observed.

Winery

Solaris

At the moment of harvest of the Solaris on September 20th, the leaves in both rows were healthy, without any signs of Oidium or Peronospera. The harvest came about a week early because of a start of Botrytis in the bunches. The Botrytis was caused by a high incidence of wasps (the result of a warm winter) who started to ‘attack’ the berries. The risk of loosing the Solaris to Botrytis was increased by a predicted rainy perdiod of 6-7 days from 20/9 onward, with temperatures around 18-20 degrees Celcius. Therefor it was decided to harvest immediate.

Because of the unplanned harvest, the sugar levels in the two rows were not measured separately. The sugar level of the combined rows was 86 Oechsle, the acidity 8.8 g/L (measured as tartaric acid). The higher than normal acidity and lower sugar levels were caused by the ‘second’ clusters, which should have had one or two weeks of sun (these were late because of the long flowering period this year). The first clusters were really ripe.

type	sugar (Oe)	acidity (g/L)
averaged	86	8,8

Marechal Foch

The Marechal Foch was harvested on October 11th. At this time (and when writing the report), the leaves in both rows were healthy, even in the top of the rows were the leaves are most dense. Based on the amount of rain in the last two months, these results came as a (positive) surprise. Fungal diseases were most probably supressed by the relatively cool temperatures.

The berry weight in both rows with ten vines was about equal; 10.6 vs 10.3 Kg for the hedged and wrapped rows respectively. Sugar and acidity levels are reported in the following table. No significant differences were observed between the two rows.

type	amount (kg)	sugar (Oe)	acidity (g/L)
hedged	10.6	79	8,2
wrapped	10.3	82	8.2

Although the sugar levels are low (which is the case for all my varieties this year), the berries showed a good phenolic ripeness. The skins were soft and tasted nice, the pips were brown and with ripe tannines.